Various abbreviations that appear in the specification and/or in the drawing figures are defined as follows:
AP access point
BS base station
CID connection identifier
CRC cyclic redundancy code
CS convergence sublayer
DCD downlink configuration descriptor
DL downlink (BS to MS)
DL-MAP downlink MAP
HT header type
IE information element
IMT international mobile telecommunications
IS infrastructure station
MAC media access control
MPDU MAC PDU
MR multi-hop relay
MS mobile station
PDU protocol data unit
R-DL-MAP relay Downlink MAP
R-MAP relay MAP
RS relay station
R-UL-MAP relay Uplink MAP
SBC-REQ SS basic capability request
SBC-RSP SS basic capability response
SS subscription station
TG task group
UCD uplink configuration descriptor
UL uplink (MS to BS)
UL-MAP uplink MAP
VoIP voice over internet protocol
WG working group
WiMAX worldwide interoperability for microwave access (IEEE 802.16 standard)
A wireless communication system may or may not include a relay node or network. One example of a relay network is a multi-hop system in which end nodes (MS/SS) are connected to the BS or AP via at least one RS. All of the traffic between the MS/SS and the BS/AP passes through and may be processed by the at least one RS. An example of such a relay concept is the 802.16 MR, which is a new study item established in the IEEE 802.16 WG. The MR-related effort focuses on defining a network system that uses RSs to extend the network coverage and/or enhance system throughput. An exemplary usage scenario of the RS is shown in FIG. 1.
In this non-limiting example, there is a BS 1, a MS 2, a SS 3 (such as a portable computer having wireless communication capability), and a RS 4. Note in this example that the MS 2 is first directly connected to the BS 1 (with no interposed RS), and after movement the MS 2 is connected to the BS 1 via the RS 4. The SS 3 is assumed for this example to be located such that it is always connected to the BS 1 via the RS 4. The BS 1 can provide connectivity to one or more communication networks, including the Internet, for enabling browsing, downloads, uploads and voice communication, such as VoIP communications, as non-limiting examples.
In general, in many different types of communication systems, when messages are transmitted from one node to another node a header is used. The header may indicate the type of message, a connection identifier and/or the type of message payload, as non-limiting examples of message header information. In IEEE 802.16 d/e (WiMAX), a generic MAC header is defined at the MAC layer. FIG. 3 shows a MAC PDU with a conventional (legacy) generic WiMAX MAC header.
Recently, new technology TGs have been created within IEEE 802.16. One is known as IEEE 802.16j (relay), which is tasked with defining the introduction of relays between the BS and MS. Another new group is IEEE 802.16m, which is tasked with defining the evolution of WiMAX and the support of IMT-A requirements.
The relay TG (IEEE 802.16j) has introduced another link, the relay link, between the BS 1 and the RS 4, and between RSs. Similarly, 802.16m is defining enhancements to the access link. Both of these approaches, however, will need to support the legacy IEEE 802.16e specifications, even though the new links may have different requirements and features and, therefore, may require new MAC headers to support enhanced features.
One approach would be to define a new header by modifying the generic MAC header. Another approach would be to define a totally new generic MAC header(s) suitable for use with the new links. However, in the first approach (modifying the generic MAC header to define a new header) there is overhead involved in using header information fields that are not relevant for the newly defined links (e.g., for the relay of 802.16m links). In addition, most of the bits in the generic MAC header are already defined for use, thereby limiting the scope of the information that can be included in the new header type.
It may therefore be preferable to define a new header or headers that are suitable for the newly defined links. However, one also needs to support legacy headers in order to continue to support legacy devices and/or legacy features for new devices.